Deletion of Lama4 accelerates AML progression. (A) Experimental layout for inducing AML by transplanting MLL-AF9 AML cells in nonirradiated young adult mice. The primary MLL-AF9 AML cells expressing CD45.1 were injected via tail vein into the CD45.2⁺Lama4^+/+ and Lama4^−/− mice at the dose of 100 000 cells per mouse. AML was monitored by blood cell counting using Sysmex, AML engraftment analysis by FACS, and spleen weight. (B) The survival rate of the Lama4^+/+- and Lama4^−/−-recipient mice after AML cell injection. The mice were found dead or moribund mice were terminated due to ethical reasons. (C) AML burden in Lama4^+/+ and Lama4^−/− mouse BM post-AML cell injection. The data shown are the percent of CD45.1⁺ cells of total live cells in BM (left) and the proportion of the mice with less or more than 20% AML cells in BM (right). The difference between the 2 groups on the right panel was determined by χ-square test. (D) The frequency of AML-initiating stem cells (LSCs) in Lama4^+/+ and Lama4^−/− mouse BM at 24 days post-AML cell injection. The LSCs were determined by the percent of KIT⁺CD45⁺ cells in the mouse BM by FACS. (E) The frequency of circulating AML cells in Lama4^+/+ and Lama4^−/− mouse PB at day 24 post-AML injection. (F) Spleen weight of Lama4^+/+ and Lama4^−/− AML mice at day 24 post-AML injection. (G) The residual host-derived CD45.2⁺ cells in BM at day 17 and 24 post-AML cell injection. (H) The residual host CD45.2⁺ cells in PB at day 24 post-AML transplantation. (I) Platelet (PLT) counts and PDW in Lama4^+/+ and Lama4^−/− mouse PB at 24 days after AML injection. (J) Experimental layout for assessing homing of the AML cells into Lama4^+/+ and Lama4^−/− mice 3 hours after transplantation. CD45.1⁺ AML cells (10 million per mouse) were transplanted into the mice via tail vein injection without prior irradiation. Blood, femurs, and spleen of the recipients were harvested 3 hours after transplantation, and homing of donor CD45.1⁺ AML cells were examined by FACS based on CD45.1 expression. (K) The frequencies of the AML cells in total nucleated cells in the recipient PB, BM, and spleen. The statistical difference was determined by an unpaired parametric Student t test. The horizontal bars represent mean values. Each dot represents the individual recipient mouse. (L) Experimental design for assessing AML relapse after transplantation of normal BM cells. The Lama4^+/+ and Lama4^−/− mice were first injected with 100 000 AML cells. On day 24 post-AML cell injection, the recipient mice were subjected to total body irradiation (TBI) followed by transplantation of 5 million normal BM MNCs. The AML relapse was then monitored by FACS of the AML burden in PB and BM. (M) The survival rate of the Lama4^+/+ and Lama4^−/− AML mice after BM transplantation. The mice were found dead or sacrificed because of a moribund state due to the fast AML relapse. (N) Percentages of AML cells in BM and PB of Lama4^+/+ and Lama4^−/− mice post-AML relapse. The analysis was done at the endpoint when the mice were moribund. The data were from 2 to 3 independent experiments. Each dot represents the data from 1 mouse. The horizontal bars are median values. The P values were determined by the Mann-Whitney U test. See also in supplemental Figures 4-6.